SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9b17f285c15329609ae5d167a5419d1095c44116e202f1ebf8638d4641ee6807' 
  AND token = 'JqSyb6r1n0bkARHt5RIbX5O3YheAAvHcskktMSNQLrQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}